It is possible to filter sites from Google search result pages using the OptimizeGoogle extension for the Firefox web browser. In order to remove sites which mirror Wikimedia content, follow the directions below:

  1. Install the OptimizeGoogle extension for Firefox from [1] Discontinued and no longer in development'
  2. Restart Firefox
  3. Copy the text from the box below
  4. Go to Tools menu -> OptimizeGoogle options... item -> Filter tab and paste the text in the text area
  5. Click OK

Please feel free to correct or add to this list.

[OptimizeGoogle]
http://tripatlas.com/*
http://*.123exp-computing.com/*
http://*.antya.com/*
http://*.able2know.org/*
http://*.alanaditescili.net/*
http://*.allexperts.com/*
http://*.allrss.com/*
http://*.absoluteastronomy.com/*
http://*.baghdadmuseum.org/ref/*
http://*.bambooweb.com/*
http://*.bookrags.com/*
http://*.biography.ms/*
http://*.biom.cz/*
http://*.brainsip.com/
http://*.brief-reklama.pl/*
http://*.cwanswers.com/*
http://*.daum.net/*
http://*.fae.sk/
http://*.fixedreference.org/*
http://*.internettexasholdem.com/*
http://*.info-reference.com/*
http://*.ipupdater.com/
http://*.iqnaut.net/
http://*.juz2u.com/* 
http://*.laborlawtalk.com/*
http://*.learnthis.info/*
http://*.linix.ca/*
http://*.liarpedia.org
http://*.localcolorart.com/*
http://*.maksiu.info/*
http://*.medbib.com/*
http://*.nationmaster.com/*
http://*.mirror.ca/*
http://*.pediax.org/*
http://*.opentopia.com/*
http://*.paellaman.com/*
http://*.prepaidcellphonez.com/*
http://*.quickseek.com/*
http://*.realtech.co.za/*
http://*.school-explorer.com/*
http://*.showmy.net/*
http://*.startplane.com/*
http://*.statemaster.com/encyclopedia/*
http://*.thehealthempire.com/*
http://*.thefullwiki.org/*
http://*.theinfoexp.com/*
http://*.vacilando.org/*
http://*.vbxml.net/*
http://*.wikimobs.com/*
http://*.wikiverse.org/*
http://*.warsearch.com/*

http://*mallforeverything.com/*
http://*mauspfeil.net/*
http://*usindexlist.de/*

http://100cia.com/*
http://10beststocks.com/*
http://aboutsat.com/*
http://academickids.com/*
http://answers.com/*
http://allrss.com/*
http://aynurkece.info/*
http://bibleocean.com/*
http://bopedia.com/*
http://bvio.ngic.re.kr/*
http://copernicus.subdomain.de/*
http://corpseclothing.com/*
http://definition-info.com/*
http://dragonholm.com/*
http://enc.slider.com/Enc/*
http://enc.tfode.com/*
http://encyclopedia.codeboy.net/*
http://encyclopedia.farlex.com/*
http://encyclopedia.laborlawtalk.com/*
http://encyclopedia.lockergnome.com/*
http://encyclopedia.mysleepcenter.com/*
http://encyclopedia.worldvillage.com/*
http://experts.about.com/e/*
http://explanation-guide.info/*
http://fact-archive.com/*
http://fixedreference.org/*
http://fr.wikibuster.org/*
http://help.com/wiki/*
http://instapedia.com/*
http://joomla.anezi.net/wiki*
http://kfmstriping.com/*
http://knowledgerush.com/kr/encyclopedia/*
http://lexikon.calsky.com/*
http://open-dictionary.com/*
http://pedia.newsfilter.co.uk/*
http://pediaview.com/*
http://pheeds.com/*
http://psychcentral.com/psypsych/*
http://reference.com/browse/wiki/*
http://thepedia.com/*
http://therfcc.org/*
http://toshare.servepics.com/*
http://ufaqs.com/wiki/*
http://valleygirl.wackipedia.com/*
http://wacklepedia.com/*
http://wapedia.mobi/*
http://wapipedia.org/*
http://websitepromotion.in/*
http://wiki.verkata.com/*
http://wiki.w2n.net/*
http://wikimobs.com/*
http://wiktionary.us/*
http://wpedia.goo.ne.jp/enwiki/*
http://yomi.mobi/egate/*

http://www.1-player.net/*
http://www.4reference.net/*
http://www.99hosted.com/*
http://www.abacci.com/wikipedia/*
http://www.abika.info/*
http://www.abitabouteverything.com/*
http://www.absoluteastronomy.com/encyclopedia/*
http://www.absoluteastronomy.com/ref/*
http://www.absoluteastronomy.com/reference/*
http://www.absoluteastronomy.com/topics/*
http://www.algebra.com/*
http://www.all-science-fair-projects.com/science_fair_projects_encyclopedia/*
http://www.amway.lt/*
http://www.anoca.org/*
http://www.answers.com/*
http://www.arthistoryclub.com/*
http://www.artpolitic.org/*
http://www.askfactmaster.com/*
http://www.biocrawler.com/encyclopedia/*
http://www.braindex.com/encyclopedia/*
http://www.brainyencyclopedia.com/*
http://www.cat-center.com/articles/*
http://www.citizendia.org/*
http://www.cooldictionary.com/*
http://www.definition-info.com/*
http://www.dictionaryofeverything.com/*
http://www.drivefor2005.org/wiki/*
http://www.easyencyclopedia.com/*
http://www.ebroadcast.com.au/lookup/encyclopedia/*
http://www.economicexpert.com/a/*
http://www.elresearch.com/*
http://www.en.wapedia.org/*
http://www.encyclopedia-online.info/*
http://www.encyclopedia4u.com/*
http://www.explainthat.info/*
http://www.explainthis.info/*
http://www.fact-archive.com/*
http://www.fact-index.com/*
http://www.factbug.org/*
http://www.famous.tc/*
http://www.freeglossary.com/*
http://www.gardeningdaily.com/*
http://www.glossary.com/*
http://www.governpub.com/*
http://www.greatestinfo.org/*
http://www.guajara.com/*
http://www.gurupedia.com/*
http://www.hondurasthisweek.com/honduras-on-wikipedia*
http://www.indexuslist.de/*
http://www.indopedia.org/*
http://www.informationclub.com/*
http://www.infothis.com/*
http://www.infowrangler.com/phpwiki/*
http://www.internet-encyclopedia.org/*
http://www.internet-encyclopedia.us/*
http://www.ipedia.com/*
http://www.irelandinformationguide.com/*
http://www.iridis.com/*
http://www.jdhodges.com/posters/*
http://www.kids.net.au/*
http://www.kidsbesafe.org/*
http://www.kiwipedia.com*
http://www.knowledgeking.net/*
http://www.knowledgerush.com/kr/encyclopedia/*
http://www.kythuatvatlieu.org/about-vietnam.html*
http://www.marijuana.com/wiki/*
http://www.masterliness.com/*
http://www.masterliness.com/a/*
http://www.mathdaily.com/*
http://www.medicalrace.com/*
http://www.museumstuff.com/learn/*
http://www.nanriver.com/*
http://www.nationmaster.com/encyclopedia/*
http://www.netzwelt.de/*
http://www.notfah.com/wiki/*
http://www.nw4u.co.uk/*
http://www.objectsspace.com/*
http://www.onelang.com/encyclopedia/*
http://www.onpedia.com/*
http://www.perfectsushi.com/en/wikipedia/*
http://www.pillnow.net/university/Library/*
http://www.reference.com/browse/wiki/*
http://www.search.com/reference/*
http://www.searchspaniel.com/*
http://www.seekj.com/*
http://www.smartpedia.com/*
http://www.teachersparadise.com/*
http://www.territorioscuola.com/wikipedia/*
http://www.thebestlinks.com/*
http://www.thefreedictionary.com/*
http://www.thepedia.com/*
http://www.thewordbook.com/*
http://www.tiosam.com/enciclopedia/*
http://www.tranexp.com:2000/*
http://www.tutorgig.com/*
http://www.ufaqs.com/wiki/*
http://www.voyager.in/*
http://www.vvvvitamins.com/*
http://www.wackipedia.com/*
http://www.webenglish.com.tw/encyclopedia/en/wikipedia/*
http://www.webscavengers.net/*
http://www.websters-online-dictionary.org/*
http://www.what-means.com/*
http://www.whatis.tv/*
http://www.wikibooks.net/*
http://www.wikipedia.it/*
http://www.wikisearch.net/*
http://www.wikiworld.biz*
http://www.wordiq.com/*
http://www.worldlingo.com/ma/enwiki/*
http://www.wordlookup.net/*
http://www.worldhistory.com/*
http://www.worldwardiary.com/*
http://www.yourart.com/research/encyclopedia*
http://www.yourencyclopedia.net/*
http://www.zwiki.com/*

Please consider not excluding an entire site or domain if there is some non-wikipedia content of value on it.

See also

edit
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HOME 1
Intern 3
iOS 2
languages 2
Note 1
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text 3
web 6